The present invention relates to paint spray booths. More particularly, the present invention relates to a paint spray booth including a wet scrubbing apparatus for removing paint overspray from the paint spray booth.
In paint spray booth operations, excess paint is created which does not adhere to the object being painted. Such excess paint or paint overspray must be removed from the paint booth to maintain a proper working environment and to prepare the booth for subsequent articles to be painted.
Wet scrubbers have proven particularly useful for the elimination of paint overspray. Wet scrubbers use a scrubbing liquid--usually water--to scrub paint particles from a stream of paint-laden air exiting the spray-painting area of a spray booth. Typically, an air stream is passed through the spray-painting area and is drawn through a floor grating. A water stream flows beneath the floor grating and impacts the paint-laden air stream in a scrubbing apparatus.
The scrubbing apparatus should be specially configured to maximize contact between the water stream and the air stream so as to provide highly effective scrubbing. Generally, the scrubbing apparatus is designed to atomize the water stream so that maximum surface area is provided for contact with paint particles in the air stream. The paint particles impact on the water droplets and form agglomerates which will not readily return to the air stream.
While the wet scrubber should be designed for effective atomization of the water stream, other design considerations must also be met. The atomization of the water stream and its impact with the paint-laden air stream create high noise levels. The problem is exacerbated by the high water flow rate (e.g., 20,000 cfm for booths of a typical length) and the high air speed (e.g., 60 mph). The scrubbing apparatus should thus provide means for containing or muffling noice to reduce the amount of noise which can return to the spray painting area of the spray booth.
In addition, the turbulent flow conditions conducive to atomization of the water can cause the water stream to splash against the surfaces of the scrubbing apparatus. Some, portions of the surfaces are contacted or "washed" by the splashing water, while other portions are likely to be left unwashed. Paint particles scrubbed out of the air stream tend to accumulate on the unwashed portions of the surfaces, forming an undesirable buildup of paint.
According to the present invention, a paint spray booth is provided with a first longitudinally extending concave plate and a second longitudinally extending concave plate arranged so as to reduce noise and minimize paint buildup. Specifically, the paint spray booth comprises a floor covered with a flowing liquid, the floor comprising means for defining an elongated passageway therein. The passageway has an upper entrance opening and a lower exit opening through which the liquid flows downwardly as a scrubbing liquid stream. The booth further comprises means for exhausting air from the booth and pulling a paint-laden air stream downwardly through the openings. The entrance opening is positioned to receive the air stream and the scrubbing liquid stream for mixing in the passageway to form a mixed stream. The passageway means comprises a pair of laterally spaced apart, longitudinally and downwardly extending passageway walls.
The booth further comprises a first and a second longitudinally extending concave plane. The first longitudinally extending concave plate is positioned under the exit opening and includes a first reflecting surface facing generally upwardly and positioned to receive the mixed stream exiting the exit opening.
The second longitudinally extending concave plate is laterally spaced apart from the first concave plate and includes a second reflecting surface facing generally downwardly and positioned to oppose the first reflecting surface. The first and second concave plates cooperate to define a longitudinally extending flow chamber and a longitudinally extending discharge opening positioned to discharge the mixed stream from the flow chamber.
Advantageously, at least lower portions of the passageway walls extend into the flow chamber. Thus, noise generated by the mixed stream at the discharge opening and reflecting from the second reflecting surface is directed toward the lower portions. This reduces the amount of noise returning to the passageway means by way of the first reflecting surface.
The present invention also relates to a method for removing paint overspray from a spray booth. The method comprises the steps of forcing a stream of paint-laden air downwardly through an entrance opening into a passageway and flowing a stream of scrubbing liquid into the passageway to mix with the stream of paint-laden air to form a mixed stream. The method further comprises the steps of flowing the mixed stream along a first concave plate, flowing the mixed stream along a second concave plate, and atomizing the mixed stream at a discharge opening to scrub paint particles from the air stream.
Additional objects, features, and advantages of the invention will become apparent to those skilled in the art upon consideration of the following detailed description of preferred embodiments exemplifying the best mode of carrying out the invention as presently perceived by the inventor.